Networks (EdExcel)
Two or more computers or electronic devices are connected for communication.
Can be connected by a wired medium (such as cables), or by a wireless medium (such as Wi-Fi)
Stand-alone is A computer or device not connected to a network.
Desktop computers, laptops, smartphones, smartwatches, fitness trackers, car engine management systems, internet-enabled fridges, intelligent personal assistants, and media boxes.
1. Software and File Sharing
Users share software and files with other users.
2. Hardware Sharing
Users share hardware, such as printers.
3. Communication
Users communicate via email, chat, or video.
4. Roaming Access
Users sign in to any computer on the network to access their files.
5. Centralised Maintenance and Updates
Network managers can apply software updates across the network, removing the need for users to do so.
6. Centralised Security
Anti-virus software and firewalls can be implemented across a network, protecting user files from risks.
7. User Monitoring
Network managers can monitor what users do on a network.
8. Levels of Access
Different users can be given different access rights, restricting or granting permissions as needed.
1. Cost
Additional equipment is needed to allow computers to communicate.
2. Management
Larger networks require management by specialist staff, such as a network manager.
3. Spread of Malware
Viruses and other forms of malware can easily spread across an improperly secured network.
4. Hacking
Once a device is connected to another device, data may be accessed without the device owner's permission.
Two classifications of network.
- Geographically confined to a single site (e.g., small businesses, schools, homes).
- Connected by wired (cables) or wireless (Wi-Fi) mediums.
- Owned and maintained by the organization.
- Spread over a wide geographical area, covering more than one site.
- Made up of two or more LANs.
- Used by organizations with multiple branches (e.g., banks) for communication and data sharing.
- Communication through national telephone infrastructures or wireless transmission.
- The internet is a massive, international WAN.
Use copper or fiber optic cables.
Fiber optic cables provide greater bandwidth and faster transfer speeds.
- Faster data transfer.
- Less interference compared to wireless.
- Harder for unauthorized users to intercept data.
- Expensive installation and reconfiguration.
- Limited mobility for devices.
Use radio signals or other methods like infrared light.
Allow easy addition of new nodes and user mobility.
- Easy addition of new nodes.
- User mobility without loss of connection.
- Limited range.
- Susceptible to electromagnetic interference and obstacles.
- Bandwidth is shared among connected nodes, slowing communication with more nodes.
- Security risks due to potential interception; encryption is needed.
- Expensive installation and reconfiguration.
- Limited mobility for devices.
Measured in bits per second (bps).
1 Mbps = 1,000,000 bits per second.
1 Gbps = 1,000,000,000 bits per second.
time = size of file (in bits) / network speed (in bits).
Rules that govern communication, including transmission speed, error checking, and addressing.
Ethernet - Used in wired LANs.
Wi-Fi - Used in wireless LANs.
TCP/IP - Enables communication over the internet.
HTTP/HTTPS - Governs web server and client communication; HTTPS includes secure encryption.
FTP - Governs file transmission across a network and the internet.
SMTP - Governs sending email to a mail server.
POP3/IMAP - Also known as Post Office Protocol and Internet Message Access Protocol; Governs retrieving emails from servers (IMAP is the newer standard).
Layering - Breaking up message sending into components/activities.
IP Addressing - Uses IPv4 (32 bits) and IPv6 (128 bits) for node addresses.
Application Layer - Encodes/decodes messages (uses HTTP, FTP, SMTP).
Transport Layer - Breaks messages into packets, and assigns numbers for reassembly.
Internet Layer - Adds IP addresses for routing and is sometimes called the network layer.
Link Layer - Handles physical transfer of packets between nodes.
- Breaking messages into packets for transmission.
Header - Includes sender/recipient IP, packet number, total packets, and protocol details.
Payload - Part of the message itself.
the arrangement, or pattern, in which all nodes on a network are connected together. The major network topologies are Bus, Ring, Star, and Mesh.
Any device connected to a network
All nodes are connected to the network either by cables or wirelessly.
All nodes joined to a single cable. At each end of the cable, a terminator is fitted to stop signals reflecting back down the bus.
Advantages: Easy and cheap to install.
Disadvantages: Main cable failure disrupts the network, data collisions slow performance, and security risk.
Nodes connected through one or more switches/hubs. The switch or hub acts as a central point through which all communications are passed.
Hub: Broadcasts a message across the whole network.
Switch: Sends the message to the intended recipient only.
Advantages: Isolated node/link failure, easy addition of nodes, high performance.
Disadvantages: Switch failure disrupts the network, expensive due to cabling.
Nodes connected to multiple other nodes. There is no central connection point.
Fully Connected Mesh: Every node is connected to every other node.
Partial Mesh: Nodes connected to some, not all.
Advantages: Reliable, multiple communication routes, simultaneous transmission/reception, easy node addition.
Disadvantages: Expensive setup, high maintenance.
Mesh Topologies in Use
Applications: Military, city monitoring, emergency services, utility companies, the internet.
Two or more computers or electronic devices are connected for communication.
Can be connected by a wired medium (such as cables), or by a wireless medium (such as Wi-Fi)
Stand-alone is A computer or device not connected to a network.
Desktop computers, laptops, smartphones, smartwatches, fitness trackers, car engine management systems, internet-enabled fridges, intelligent personal assistants, and media boxes.
1. Software and File Sharing
Users share software and files with other users.
2. Hardware Sharing
Users share hardware, such as printers.
3. Communication
Users communicate via email, chat, or video.
4. Roaming Access
Users sign in to any computer on the network to access their files.
5. Centralised Maintenance and Updates
Network managers can apply software updates across the network, removing the need for users to do so.
6. Centralised Security
Anti-virus software and firewalls can be implemented across a network, protecting user files from risks.
7. User Monitoring
Network managers can monitor what users do on a network.
8. Levels of Access
Different users can be given different access rights, restricting or granting permissions as needed.
1. Cost
Additional equipment is needed to allow computers to communicate.
2. Management
Larger networks require management by specialist staff, such as a network manager.
3. Spread of Malware
Viruses and other forms of malware can easily spread across an improperly secured network.
4. Hacking
Once a device is connected to another device, data may be accessed without the device owner's permission.
Two classifications of network.
- Geographically confined to a single site (e.g., small businesses, schools, homes).
- Connected by wired (cables) or wireless (Wi-Fi) mediums.
- Owned and maintained by the organization.
- Spread over a wide geographical area, covering more than one site.
- Made up of two or more LANs.
- Used by organizations with multiple branches (e.g., banks) for communication and data sharing.
- Communication through national telephone infrastructures or wireless transmission.
- The internet is a massive, international WAN.
Use copper or fiber optic cables.
Fiber optic cables provide greater bandwidth and faster transfer speeds.
- Faster data transfer.
- Less interference compared to wireless.
- Harder for unauthorized users to intercept data.
- Expensive installation and reconfiguration.
- Limited mobility for devices.
Use radio signals or other methods like infrared light.
Allow easy addition of new nodes and user mobility.
- Easy addition of new nodes.
- User mobility without loss of connection.
- Limited range.
- Susceptible to electromagnetic interference and obstacles.
- Bandwidth is shared among connected nodes, slowing communication with more nodes.
- Security risks due to potential interception; encryption is needed.
- Expensive installation and reconfiguration.
- Limited mobility for devices.
Measured in bits per second (bps).
1 Mbps = 1,000,000 bits per second.
1 Gbps = 1,000,000,000 bits per second.
time = size of file (in bits) / network speed (in bits).
Rules that govern communication, including transmission speed, error checking, and addressing.
Ethernet - Used in wired LANs.
Wi-Fi - Used in wireless LANs.
TCP/IP - Enables communication over the internet.
HTTP/HTTPS - Governs web server and client communication; HTTPS includes secure encryption.
FTP - Governs file transmission across a network and the internet.
SMTP - Governs sending email to a mail server.
POP3/IMAP - Also known as Post Office Protocol and Internet Message Access Protocol; Governs retrieving emails from servers (IMAP is the newer standard).
Layering - Breaking up message sending into components/activities.
IP Addressing - Uses IPv4 (32 bits) and IPv6 (128 bits) for node addresses.
Application Layer - Encodes/decodes messages (uses HTTP, FTP, SMTP).
Transport Layer - Breaks messages into packets, and assigns numbers for reassembly.
Internet Layer - Adds IP addresses for routing and is sometimes called the network layer.
Link Layer - Handles physical transfer of packets between nodes.
- Breaking messages into packets for transmission.
Header - Includes sender/recipient IP, packet number, total packets, and protocol details.
Payload - Part of the message itself.
the arrangement, or pattern, in which all nodes on a network are connected together. The major network topologies are Bus, Ring, Star, and Mesh.
Any device connected to a network
All nodes are connected to the network either by cables or wirelessly.
All nodes joined to a single cable. At each end of the cable, a terminator is fitted to stop signals reflecting back down the bus.
Advantages: Easy and cheap to install.
Disadvantages: Main cable failure disrupts the network, data collisions slow performance, and security risk.
Nodes connected through one or more switches/hubs. The switch or hub acts as a central point through which all communications are passed.
Hub: Broadcasts a message across the whole network.
Switch: Sends the message to the intended recipient only.
Advantages: Isolated node/link failure, easy addition of nodes, high performance.
Disadvantages: Switch failure disrupts the network, expensive due to cabling.
Nodes connected to multiple other nodes. There is no central connection point.
Fully Connected Mesh: Every node is connected to every other node.
Partial Mesh: Nodes connected to some, not all.
Advantages: Reliable, multiple communication routes, simultaneous transmission/reception, easy node addition.
Disadvantages: Expensive setup, high maintenance.
Mesh Topologies in Use
Applications: Military, city monitoring, emergency services, utility companies, the internet.
